I bought about eight 5/8" thick 8" wide cedar boards to cut up and use for slats to rebuild my mountain cabin deck railing. They have lots of knots in them How can I make sure they don't fall out later on? The slats will only be about 2.5"-4" wide. Thought I read years ago painting each knot with shellac might help but my memory is very faulty. The slats will be oil primed and painted before installation. Any ideas? Randy